Ajay’s plant was 11 centimetres tall. It grows seven centimetres taller. How tall is the plant now?
This question is like a before and after question. We know what the height of Ajay’s plant was. And we need to find out how tall it is now. Ajay’s plant was 11 centimetres tall. It grows seven centimetres taller. In other words, the height is now seven centimetres more. We could draw a bar model to help us show the change in height and to help us understand how to work out the answer. Because we’re talking about the height of something, let’s draw the bar model vertically. This will help us to visualize the plant growing.
Ajay’s plant was 11 centimetres tall. And we know that it grew another seven centimetres. So how can we work out the height of the plant now? Our bar model shows the change in the height. This is why it’s a before and after question. The height was 11 centimetres. And then it became seven centimetres more. So we need to add those two numbers together. What is 11 plus seven?
There are some really quick ways to answer this question and they all involve thinking about facts that we already know. For example, if we know what 10 plus seven is, we can use it quickly to find what 11 plus seven is. 10 plus seven equals 17. So 11 plus seven must be one more than this. The answer is 18. Another really quick way to find the answer is to look at the ones digit first. If we know what one plus seven is, we can use it to help find the answer to what 11 plus seven is. One plus seven equals eight. And so straightaway, we can see that 11 plus seven must equal 18. There are other ways we could find the answer. But those are two of the quickest.
Ajay’s plant was 11 centimetres tall. It grows seven centimetres taller. And the height of the plant now is 18 centimetres. 11 centimetres plus seven centimetres equals 18 centimetres.